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Asian Carp and the Headwaters of the Mississippi

The Navigation of the Mischasippi is interrupted ten Leagues above this River of the Grave, by a Fall of fifty or sixty Foot, which we call’d The Fall of St. Anthony of Padua, whom we had taken for the Protector of our Discovery. There is a Rock of a Pyramidal Figure, just in the middle of the fall of the River.” –Father Louis Hennepin, 1680

“From the river St. Peters to the falls of St. Anthony, the river is contracted between high hills, and is one continual rapid or fall, the bottom being covered with rocks which (in low water) are some feet above the surface, leaving narrow channels between them. The rapidity of the current is likewise much augmented by the numerous rocky islands, which obstruct the navigation.” –Lt. Zebulon Pike, 1805

Dam at the Falls of St. Anthony

Ten thousand years before Father Louis Hennepin came upon the Falls of St. Anthony and named them, River Warren “poured over the Big Stone Moraine at Browns Valley, Minnesota and scoured the Minnesota River gorge to bedrock. When it entered a buried river channel at St. Paul, River Warren Falls developed and retreated upstream, gnawing away at the soft sandstone that lay under the limestone cap. The caprock collapsed, creating the Mississippi gorge between St. Paul and Fort Snelling. At Fort Snelling River Warren Falls eroded past the entrance to the Mississippi and created the Falls of St. Anthony, a tributary waterfall, which eroded the sandstone under the limestone caprock, leaving a gorge filled it with fallen blocks of limestone between Fort Snelling and Minneapolis.”

European explorers found a gorge filled with rapids that dropped seventy-three feet in elevation over the course of seven miles. While navigation through the rapids was often impossible, they provided an excellent spawning ground for fish and mussels.

In 1680 the Falls of St. Anthony were the geological and biological breakpoint between the headwaters of the Mississippi and the Upper Mississippi. Of the 123 species of fish that swim the Mississippi below the falls, fifty-nine have never ventured above the falls. Channel catfish, ubiquitous between St. Paul and Louisiana, never breached the falls to inhabit the headwaters, nor did lake sturgeon or white bass or brook trout, though brook trout was introduced at a later date.

Had Minneapolis never become the flour milling capital of the United Stated in the 1880s and built a stabilization dam to harness the power of the Falls of St. Anthony to grind grain, the tributary waterfall would have continued its retreat upstream and eventually peter out into a rapids where the limestone caprock came to an end.

Had Minneapolis never had ambitions to become the head of navigation on the Upper Mississippi and built pair of locks and dams to extend navigation four and a half miles above the falls, the Asian Carp would not be threatening the Headwaters of the Mississippi.

Two locks and dams ease the passage of barges through the gorge between Fort Snelling and Minneapolis. The first the Ford Dam was built in 1917; the Corps of Engineers completed the second at the Falls of St. Anthony in 1963. Environmentalists and local and state officials who see the Asian carp headed their way, want to see the locks on the two dams closed. What barges can’t pass through, carp can’t pass through. Silver carp dna has been found in the St. Croix River and a commercial fisher caught a bigheaded carp in the St. Croix. However, no carp dna has been found at Hidden Falls just south of the Ford Dam, the first barrier to the fish passage up the Mississippi.

Blackhoof Lake near Ironton, Minnesota

Environmentalists in Minnesota have the same concerns as those in Michigan: should the carp pass through the geological and biological break that are the Falls of St. Anthony or rather the Lock and Dam at the falls, the fish will invade the headwater fishing grounds, a labyrinth of lakes and streams connected to the Mississippi, and change the ecological balance of the headwaters.

Elk River, tea-colored from runoff from surrounding bogs


[i]             Hennepin, 223.

[ii]             Pike, Appendix to Part I, 50.

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